Extensive Degradation and Low Bioavailability of Orally Consumed Corn miRNAs in Mice

Area of Science:

• Molecular Biology
• Genetics
• Nutrition Science

Background:

• Conflicting literature exists regarding the cross-kingdom transfer of plant microRNAs (miRNAs) into mammals.
• Understanding miRNA bioavailability is crucial for assessing dietary nucleic acid safety and efficacy.
• Improved methods for miRNA detection are needed to resolve previous discrepancies.

Purpose of the Study:

• To resolve discrepancies in the literature concerning plant miRNA transfer into mammals.
• To investigate the bioavailability of plant miRNAs in a mammalian model using an improved detection method.
• To determine if dietary corn miRNAs increase in mouse blood and tissues.

Main Methods:

• Two studies using C57BL/6 mice were conducted with different dietary interventions (corn miRNA gavage, corn powder supplementation).
• Quantitative real-time PCR (RT-PCR) with artifact elimination treatments was used to analyze corn miRNA levels.
• In vitro digestion models assessed miRNA stability in the gastrointestinal tract.

Main Results:

• After removing false positives, no significant differences in corn miRNA levels were found in cecal, fecal, liver, or blood samples between control and treated groups.
• In vitro digestion demonstrated extensive degradation of corn miRNAs, with less than 1% recovery in the gastrointestinal tract.
• Dietary supplementation with corn miRNAs did not lead to detectable increases in mouse blood or tissue samples.

Conclusions:

• The study found no evidence supporting the cross-kingdom transfer and systemic bioavailability of plant miRNAs from corn into mice.
• Improved miRNA detection methods confirmed the absence of increased plant miRNA levels in vivo.
• Extensive degradation of plant miRNAs in the gastrointestinal tract limits their potential for systemic absorption.